Explanation:
a- for 15 biscuits:
sugar=60g
for 60 biscuits, she will need:
sugar=240, as she would make 15 biscuits 4 times to get a total of 60 biscuits
the amount of flour must be 3×sugar used
so amount of flour she needs is 720g
b i- she needs a total of 480g butter as butter is 2× of sugar used
ii- since she buys in 250g packs, she would have to buy 2 packs
20 g will be left after she finishes making the biscuits